A. Field of Invention
This invention pertains to a method and apparatus for storing multichannel audio programs such as recordings of DVDs and other similar media. More particularly, the present invention pertains to a method and apparatus for determining coefficients useful for down-converting multichannel recordings to a dual channel (right/left) stereo recording. The coefficients thus obtained are recorded on the respective media together with program and other data as well.
B. Description of the Prior Art
Standard recordings of audio programs, for example for DVD or other modern high quality recording media are normally include up to six or even more channels. The standard six channels are generally termed as left front (LF), right front (RF), left rear (LR), right rear (RR), center (C) and subwoofer (SW). A problem with this type of recording is that in some instances, for example, in a car, or in other environments, such a high quality is not required and a lower quality dual channel stereo reproduction (left and right) is sufficient. Other types of equipment were dual channels may be sufficient include most portable stereos, boom boxes, personal stereos such as the Walkman®, table top radios, and so forth. Multichannel recording can be converted to two channels by the respective playing equipment using, for example, a set of either preset, or arbitrary coefficients. However, this type of conversion is very inaccurate and results in sounds which may not be acceptable to consumers. Moreover, it is the interest of the producer and artist recording a program to insure that the programs are played back as accurately as possible and without unduly compromising the artistic rendition of the respective musical work. If the down conversion takes place using standardized or arbitrary coefficients, the artist and/or producer loses control over the modified program.
In order to insure uniformity and compatibility between various program recording and playback equipment various national and international organizations have promulgated standards for data formatting and other aspects of recording programs on media. Some of these standards include designations for down converting coefficients as well. However, the standards do not specify how the coefficients are to be determined.